The letter, which sources said was received through fax, has sought details of cases of ``kidnappings for ransom, extortions and murders organised by Irfan Goga, Abu Salem, Chotta Shakeel and other members of the Dawood Ibrahim gang''. Besides details of cases registered by the police, the CBI has also asked for intelligence inputs on crimes involving Dawood's men and interrogation reports of persons who were arrested, sources said.

``It is likely that in many instances formal cases have not been registered but intelligence inputs have been received. It is, therefore requested that brief facts of all instances, whether registered or not registered, may be sent to us giving brieffacts of the cases and the ultimate outcome,'' Mishra has written.

Sources confirmed that the letter was sent to the Director Generals of Punjab and Haryana Police and seven other states, the Commissioners of Delhi and Mumbai police and the Inspector General of Chandigarh Police.

``We received the letter yesterday and have directed the intelligence staff to collect the information required and prepare a special report,'' a senior officer here said.